Wearable Heads Up Displays

ABSTRACT

An optical display, including a first waveguide having a first set of surfaces, an input grating, a fold grating, and an output grating; an image input image node assembly; and a prismatic relay optics is provided. The prismatic relay optics may be configured to be optomechanically connected to the waveguide and the input image node assembly. The optical display is may also be configured to operate alone or as integrated with a headpiece to be used as a HUD. The HUD may have a first and a second configuration wherein the waveguide is decoupled or coupled.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Pat. Application No.17/457,891, entitled “Wearable Heads Up Displays” to Waldern et al.,filed Dec. 6, 2021, which application is a continuation of U.S. Pat.Application No. 17/118,316, entitled “Wearable Heads Up Displays” toWaldern et al., filed Dec. 10, 2020, which application is a continuationof U.S. Pat. Application No. 16/773,585, entitled “Wearable Heads UpDisplays” to Waldern et al., filed Jan. 27, 2020, which application is acontinuation of U.S. Pat. Application No. 15/863,798, entitled “WearableHeads Up Displays” to Waldern et al., filed Jan. 5, 2018, whichapplication claims priority to U.S. Provisional Pat. Application No.62/498,715, entitled “Waveguide Displays” to Waldern et al., filed Jan.5, 2017, the disclosures of which are incorporated herein by referencein their entireties.

FIELD OF THE INVENTION

The present invention relates generally to displays including but notlimited to near eye displays and more specifically holographic waveguidedisplays. Additionally, the present invention deals directly with theapplication of such displays in protective helmets.

BACKGROUND

Waveguide optics is currently being considered for a range of displayand sensor applications for which the ability of waveguides to integratemultiple optical functions into a thin, transparent, lightweightsubstrate is of key importance. This new approach is stimulating newproduct developments including near-eye displays for Augmented Reality(AR) and Virtual Reality (VR), compact Heads Up Display (HUDs) foraviation and road transport and sensors for biometric and laser radar(LIDAR) applications. Waveguide displays have been proposed which usediffraction gratings to preserve eye box size while reducing lens size.U.S. Pat. No. 4,309,070 issued to St. Leger Searle and U.S. Pat. No.4,711,512 issued to Upatnieks disclose substrate waveguide head updisplays where the pupil of a collimating optical system is effectivelyexpanded by the waveguide structure. U.S. Pat. Application No.13/869,866 discloses holographic wide angle displays and U.S. Pat.Application No. 13/844,456 discloses waveguide displays having an upperand lower field of view.

A common requirement in waveguide optics is to provide beam expansion intwo orthogonal directions. In display applications this translates to alarge eyebox. While the principles of beam expansion in holographicwaveguides are well established dual axis expansion requires separategrating layers to provide separate vertical and horizontal expansion.One of the gratings, usually the one giving the second axis expansion,also provides the near eye component of the display where the hightransparency and thin, lightweight form factor of a diffractive opticscan be used to maximum effect. In practical display applications, whichdemand full color and large fields of view the number of layers requiredto implement dual axis expansion becomes unacceptably large resulting inincreased thickness weight and haze. Solutions for reducing the numberof layers based on multiplexing two or more gratings in a single layeror fold gratings which can perform dual axis expansion (for a givenangular range and wavelength) in a single layer are currently indevelopment. Dual axis expansion is also an issue in waveguides forsensor applications such as eye trackers and LIDAR. There is arequirement for a low cost, efficient, compact dual axis expansionwaveguide.

The use of HUD’s in the motor industry is increasing in popularityespecially in the motorcycle and recreational sport vehicle industry.Such industry applications enable the user to maintain focus on the roador surrounding environment while also receiving information about theusers speed, engine conditions, phone calls, and possibly otherextrinsic information that would otherwise divert the user’s attentionthrough the use of other external devices. The application of suchdisplays is becoming essential for increased safety of the user and as awhole.

SUMMARY OF THE INVENTION

An optical display HUD is disclosed. In one embodiment an opticaldisplay, comprises a first waveguide having a first set of surfacescomprising a first open space disposed therebetween; at least one inputgrating disposed between the first set of surfaces and configured toreceive an image from an Input Image Node assembly; at least one foldgrating optically connected to the at least one input grating anddisposed between the first set of surfaces; at least one output gratingoptically connected to the at least one fold grating and disposedbetween the first set of surfaces; a prismatic relay opticsopto-mechanically disposed between the input image node assembly and thefirst waveguide; an opto-mechanical coupler disposed between theprismatic relay optics and the input image node assembly, wherein thefirst opto-mechanical coupler is configured to support the prismaticrelay optics and receive a collimated first wavelength image modulatedlight and to cause the light to travel within the prismatic relay opticsvia total internal reflections to the first waveguide; and an opticalinterface coupler disposed between the prismatic relay optics and thefirst waveguide wherein the optical interface coupler is configured toreceive the wavelength image modulated light as reflected within theprismatic relay optics and optically communicate said image to the firstwaveguide wherein the image will be reflected within the first waveguidevia total internal reflection between said first set of surfaces fromthe at least one input grating to the fold grating; wherein said foldgrating is configured to provide pupil expansion in a first directionand to direct said light to the output grating via total internalreflection between the first set of surfaces; and wherein said outputgrating is configured to provide pupil expansion in a second directiondifferent than said first direction and to cause said light to exit saidfirst waveguide from said first set of surfaces.

In other embodiments the input image node assembly further comprises anouter body having a thickness and an internal cavity wherein disposedwithin the cavity is at least one light source and at least onemicrodisplay panel for displaying image pixels and collimation optics,and wherein the input image node assembly is configured to project animage displayed on said microdisplay panel within the prismatic relayoptics at a critical angle unique thereby ensuring the image istransmitted to the waveguide at the critical angle thus preserving thetotal internal reflection of the image..

In still other embodiments gratings of the optical display areswitchable between a diffracting and non-diffracting state.

In yet other embodiments the optical display further comprises a secondwaveguide comprising a second set of surfaces having a second open spacethere between and, an input grating, a fold grating, and an outputgrating, wherein the input coupler is configured to receive a secondwavelength light from the input image node assembly.

In yet still other embodiments the gratings comprised of a liquidcrystal-based grating.

In even still other embodiments the optical display further comprises aneye tracker.

In other embodiments the optical display further comprises a dynamicfocus lens disposed within the Input image node assembly.

In still other embodiments the optical display further comprises adynamic focus lens disposed in proximity to the first set of surfaces ofthe first waveguide.

In yet still other embodiments the opto-mechanical coupler and theoptical interface coupler are configured to be coupled or decoupled viaat least one mechanical interface wherein the at least one mechanicalinterface of the opto-mechanical coupler is disposed between theopto-mechanical coupler and the input image node assembly and the atleast one mechanical interface of the optical interface coupler isdisposed between the optical interface coupler and the prismatic relayoptics.

In yet still other embodiments the at least one mechanical interface ofeach of the opto-mechanical coupler and optical interface coupler isselected from a group consisting of hinged and magnetic.

In even still other embodiments the first waveguide is disposable.

In other embodiments the first set of surfaces are a ballistic shatterproof polymer.

In still other embodiments the first set of surfaces are planarsurfaces.

In yet still other embodiments the first set of surfaces are curved.

In yet other embodiments the input image node assembly further comprisesa laser scanner.

In even other embodiments the display is further configured to beremovably connected to a headpiece.

In yet even other embodiments the input image node assembly is furtherconfigured to be adjustably connected to the headpiece such that thewaveguide may be optimally adjusted and wherein the waveguide may bedecoupled for replacement or storage.

In other embodiments the input image node assembly is configured to beintegrated within an internal protection material of a helmet.

In yet other embodiments the input image node assembly is furtherconfigured to be adjustable such that the waveguide may be optimallyadjusted.

In still other embodiments the waveguide is configured to be adjustablesuch that the rake angle may be optimally adjusted.

In yet still other embodiments the headpiece is configured to beinserted into a helmet.

In even other embodiments the input image node assembly is furtherconfigured to removably connect to a helmet having at least an outershell and at least an internal protection material and anelectromechanical connection assembly disposed within the helmet eitherconnected to the outer shell or integrated within the internalprotection material and where the input image node assembly iselectromechanically connected to the helmet.

In even still other embodiments the input image node assembly furthercomprises HDMI and power connections disposed therein wherein the HDMIand power connections are configured to connect to an equivalentconnection in the electromechanical connection assembly disposed withinthe helmet.

In other embodiments at least one of said input coupler, fold gratingand output grating multiplexes at least one of color or angle.

In yet other embodiments the optical display further comprises a beamhomogenizer

In still other embodiments the display includes at least one opticaltraversing a gradient index image transfer waveguide.

In yet still other embodiments the optical display further comprises adichroic filter disposed between the input grating regions of said firstand second waveguides.

In even other embodiments the input image node assembly furthercomprises a spatially-varying numerical aperture component for providinga numerical aperture variation along a direction corresponding to thefield of view coordinate diffracted by said input coupler.

In even still other embodiments the spatially-varying numerical aperturecomponent has at least one of diffractive, birefringent, refracting orscattering characteristics.

In other embodiments the field of view coordinate is the horizontalfield of view of the display.

In yet other embodiments a spatially varying-numerical aperture isprovided by tilting a stop plane such that its normal vector is alignedparallel to the highest display field angle in the plane containing thefield of view coordinate diffracted by said input coupler.

In still other embodiments the at least one of said input coupler, saidfold grating or said output grating is a rolled k-vector grating.

In yet still other embodiments the thickness of the outer body of theIIN does not exceed 2 mm.

In even other embodiments the input image node assembly furthercomprises a cooling fan configured to move ambient air from outside theinput image node assembly through the internal components of theassembly thereby maintaining an optimum temperature of the input imagenode assembly.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the invention. A further understanding of thenature and advantages of the present invention may be realized byreference to the remaining portions of the specification and thedrawings, which forms a part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The description and claims will be more fully understood with referenceto the following figures and data graphs, which are presented asexemplary embodiments of the invention and should not be construed as acomplete recitation of the scope of the invention.

FIG. 1 is a schematic cross section view of a waveguide display in oneembodiment.

FIG. 2 is a schematic plan view of a waveguide display shown thedisposition of the gratings in one grating layer in one embodiment.

FIG. 3 is a schematic plan view of a waveguide display shown thedisposition of the gratings in two grating layers in one embodiment.

FIG. 4 is a schematic cross section view of a color waveguide displayusing one waveguide per color and two grating layers in each waveguidein one embodiment.

FIG. 5 is a schematic cross section view of a color waveguide displayusing one waveguide per color and one grating layer in each waveguide inone embodiment.

FIG. 6 is a cross section view of an eye tracked near eye displayaccording to the principles of the invention in one embodiment.

FIG. 7 is a cross section view of an eye tracked near eye displayincorporating a dynamic focus lens in one embodiment.

FIG. 8 is a cross section view of an eye tracked near eye displayincorporating a dynamic focus lens in one embodiment.

FIG. 9 is a schematic cross section view of a reflective microdisplayinput image node containing a spatially-varying numerical aperturecomponent in one embodiment.

FIG. 10 is a schematic cross section view of a spatially-varyingnumerical aperture component based on a wedge prism in one embodiment.

FIG. 11 is a schematic cross section view of a spatially-varyingnumerical aperture component based on a wedge prism with one curvedsurface in one embodiment.

FIG. 12 is a schematic cross section view of a spatially-varyingnumerical aperture component based on an array of prisms in oneembodiment.

FIG. 13 is a schematic cross section view of a spatially-varyingnumerical aperture component based on an array of lenses in oneembodiment.

FIG. 14A is a schematic cross section view of a spatially-varyingnumerical aperture component based on an array of scattering elements inone embodiment.

FIG. 14B is a schematic cross section view of a spatially-varyingnumerical aperture component based on a substrate with a continuouslyvarying scattering function in one embodiment.

FIG. 14C is a schematic cross section view of a spatially-varyingnumerical aperture component based on a substrate with a continuouslyvarying birefringence tensor in one embodiment.

FIG. 14D is a schematic cross section view of a spatially-varyingnumerical aperture component based on an array of grating elements inone embodiment

FIG. 15 is a schematic cross section view of an optical arrangement forproviding varying numerical aperture across a pupil using a tilted pupilplane in one embodiment.

FIG. 16A is a front view of a waveguide component showing the input,fold and output gratings in one embodiment.

FIG. 16B is a front view of a waveguide component showing the input,fold and output gratings in one embodiment.

FIG. 17 is a front view of a waveguide component showing the input, foldand output gratings in one embodiment.

FIG. 18A is a schematic plan view of a first operational state displaycomprising a waveguide that can be decoupled from the IIN in oneembodiment.

FIG. 18B is a schematic plan view of a second operational state wherethe waveguide is decoupled from the IIN.

FIG. 19A is a three-dimensional view of a first operational state of awearable display comprising a retractable waveguide in one embodiment.

FIG. 19B is a three-dimensional view of a second operational state of awearable display comprising a retractable waveguide in one embodiment.

FIG. 19C is a three-dimensional view of a third operational state of awearable display comprising a retractable waveguide in one embodiment.

FIG. 20A is a front view of a waveguide display eyepiece in oneembodiment.

FIG. 20B is a plan view of a waveguide display eyepiece in oneembodiment.

FIG. 20C is a side view of a waveguide display eyepiece in oneembodiment.

FIG. 20D is a three-dimensional view of a waveguide display eyepiece inone embodiment.

FIG. 21A is a three-dimensional view of a waveguide display implementedin a motorcycle helmet in one embodiment.

FIG. 21B is a three-dimensional view of a waveguide display implementedin a motorcycle helmet in one embodiment.

FIG. 22 is a three-dimensional view of a near eye display showing a raytrace from the IIN and waveguide component up to the eye box in oneembodiment.FIG. 11A is a rolled K-vector grating providing stepwisechanges in K-vector direction in one embodiment.

FIG. 23A is a three-dimensional view of a first operational state of amotorcycle display in one embodiment.

FIG. 23B is a three-dimensional view of a second operational state of amotorcycle display in one embodiment.

FIG. 24 is a schematic plan view of a transparent wearable displayincluding prismatic relay optics for providing enhance peripheralexternal field of view in one embodiment.

FIG. 25 is a table providing a specification for a motorcycle helmet HUDin one exemplary embodiment.

FIG. 26A is a schematic front elevation view of a motorcycle helmet HUDin one exemplary embodiment.

FIG. 26B is a schematic side elevation view of a motorcycle helmet HUDin one exemplary embodiment.

FIG. 27 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 28 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 29 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 30 is a three-quarter view of a motorcycle helmet HUD in oneexemplary embodiment.

FIG. 31 is a plan view of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 32 is a three-quarter view of a motorcycle helmet HUD in oneexemplary embodiment.

FIG. 33 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 34 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 35 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 36 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 37 is a detail of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 38 is a plan view of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 39 is an overhead view of a motorcycle helmet HUD in one exemplaryembodiment.

FIG. 40A illustrates a detail of the mechanism for attaching thewaveguide eyepiece to the IIN in one embodiment.

FIG. 40B illustrates a detail of the mechanism for attaching thewaveguide eyepiece to the IIN in one embodiment.

FIG. 40C illustrates a detail of the mechanism for attaching thewaveguide eyepiece to the IIN in one embodiment.

FIG. 40D illustrates a detail of the mechanism for attaching thewaveguide eyepiece to the IIN in one embodiment.

FIG. 40E illustrates a detail of the mechanism for attaching thewaveguide eyepiece to the IIN in one embodiment.

FIG. 40F illustrates a detail of the mechanism for attaching thewaveguide eyepiece to the IIN in one embodiment.

FIG. 41A illustrates a detail of the basic helmet integration of oneembodiment

FIG. 41B illustrates the optical path of the image produced from theIIN.

FIG. 42A illustrates one embodiment of the IIN.

FIG. 42B Illustrates an embodiment of the opto-mechanical connectionbetween the IIN and the prismatic relay.

FIG. 43A illustrates another view of the opto-mechanical connectionbetween the IIN and prismatic relay.

FIG. 43B illustrates another view of the opto-mechanical connectionbetween the IIN and prismatic relay.

FIG. 44A illustrates one embodiment of the HUD connection to a helmet

FIG. 44B illustrates an alternate view of the HUD connection to a helmetas well as one embodiment of the internal components of the IIN.

FIG. 45 illustrates a method of attachment in accordance with someembodiments.

FIG. 46 illustrates top and orthogonal views of the positioning of thewaveguide with respect to corrective lenses.

FIG. 47A illustrates an alternate view of the HUD placement in a helmetin spacial relation to the wearer’s corrective lenses.

FIG. 47B illustrates an alternate view of the HUD placement in a helmetin spacial relation to the wearer’s corrective lenses.

FIG. 48 illustrates the mechanism by which the HUD connects to a bracketin accordance with some embodiments.

FIG. 49A illustrated one embodiment of the internal configuration of theIIN.

FIG. 49B illustrates an alternate view of the HUD and variouscomponents.

FIG. 50A illustrates an embodiment of the HUD integrated with a helmet.

FIG. 50B Illustrates an embodiment of the HUD configuration.

FIG. 51 illustrates various components of the HUD / Helmetconfiguration.

FIG. 52 is a schematic view of a waveguide display with a correctionelement for compensating for windscreen curvature distortion in oneembodiment.

DETAILED DESCRIPTION

Referring generally to the Figures, systems and methods relating tonear-eye display or head up display systems are provided according tovarious embodiments. Holographic waveguide technology can be utilized inwaveguides for helmet mounted displays or head mounted displays (HMDs)and head up displays (HUDs) for many applications, including militaryapplications and consumer applications (e.g., augmented reality glasses,etc.). Switchable Bragg gratings (SBGs) may be used in waveguides toeliminate extra layers and to reduce the thickness of current displaysystems, including HMDs, HUDs, and other near eye displays and toincrease the field of view by tiling images presented sequentially on amicrodisplay. A larger exit pupil may be created by using fold gratingsin conjunction with conventional gratings to provide pupil expansion ona single waveguide in both the horizontal and vertical directions. Usingthe systems and methods disclosed herein, a single optical waveguidesubstrate may generate a wider field of view than found in currentwaveguide systems. Diffraction gratings may be used to split anddiffract light rays into several beams that travel in differentdirections, thereby dispersing the light rays.

In various embodiments, the grating used in the invention is a Bragggrating (also referred to as a volume grating). Bragg gratings have highefficiency with little light being diffracted into higher orders. Therelative amount of light in the diffracted and zero order can be variedby controlling their refractive index modulation of the grating, aproperty which is used to make lossy waveguide gratings for extractinglight over a large pupil. One class of gratings is known as SwitchableBragg Gratings (SBG). SBGs are fabricated by first placing a thin filmof a mixture of photopolymerizable monomers and liquid crystal materialbetween parallel glass plates. One or both glass plates supportelectrodes, typically transparent indium tin oxide films, for applyingan electric field across the film. A volume phase grating is thenrecorded by illuminating the liquid material (often referred to as thesyrup) with two mutually coherent laser beams, which interfere to form aslanted fringe grating structure. During the recording process, themonomers polymerize and the mixture undergoes a phase separation,creating regions densely populated by liquid crystal micro-droplets,interspersed with regions of clear polymer. The alternating liquidcrystal-rich and liquid crystal-depleted regions form the fringe planesof the grating. The resulting volume phase grating can exhibit very highdiffraction efficiency, which may be controlled by the magnitude of theelectric field applied across the film. When an electric field isapplied to the grating via transparent electrodes, the naturalorientation of the LC droplets is changed causing the refractive indexmodulation of the fringes to reduce and the hologram diffractionefficiency to drop to very low levels. Typically, SBG Elements areswitched clear in 30 µs. With a longer relaxation time to switch ON.Note that the diffraction efficiency of the device can be adjusted, bymeans of the applied voltage, over a continuous range. The deviceexhibits near 100% efficiency with no voltage applied and essentiallyzero efficiency with a sufficiently high voltage applied. In certaintypes of HPDLC devices magnetic fields may be used to control the LCorientation. In certain types of HPDLC phase separation of the LCmaterial from the polymer may be accomplished to such a degree that nodiscernible droplet structure results. A SBG may also be used as apassive grating. In this mode its chief benefit is a uniquely highrefractive index modulation.

SBGs may be used to provide transmission or reflection gratings for freespace applications. SBGs may be implemented as waveguide devices inwhich the HPDLC forms either the waveguide core or an evanescentlycoupled layer in proximity to the waveguide. The parallel glass platesused to form the HPDLC cell provide a total internal reflection (TIR)light guiding structure. Light is coupled out of the SBG when theswitchable grating diffracts the light at an angle beyond the TIRcondition. Waveguides are currently of interest in a range of displayand sensor applications. Although much of the earlier work on HPDLC hasbeen directed at reflection holograms transmission devices are provingto be much more versatile as optical system building blocks. Typically,the HPDLC used in SBGs comprise liquid crystal (LC), monomers,photoinitiator dyes, and coinitiators. The mixture frequently includes asurfactant. The patent and scientific literature contains many examplesof material systems and processes that may be used to fabricate SBGs.Two fundamental patents are: U.S. Pat. No. 5,942,157 by Sutherland, andU.S. Pat. No. 5,751,452 by Tanaka et al. Both filings describe monomerand liquid crystal material combinations suitable for fabricating SBGdevices. One of the known attributes of transmission SBGs is that the LCmolecules tend to align normal to the grating fringe planes. The effectof the LC molecule alignment is that transmission SBGs efficientlydiffract P polarized light (i.e., light with the polarization vector inthe plane of incidence) but have nearly zero diffraction efficiency forS polarized light (i.e., light with the polarization vector normal tothe plane of incidence. Transmission SBGs may not be used atnear-grazing incidence as the diffraction efficiency of any grating forP polarization falls to zero when the included angle between theincident and reflected light is small.

Waveguide Displays

In accordance with various embodiments waveguide displays may take on avariety of configurations. Illustrated in FIG. 1 there is provided adual axis expansion waveguide display configuration 100 comprising alight source 101 a microdisplay panel 102 and an input image node (IIN)103 optically coupled to a waveguide 104. In such embodiments, thewaveguide may comprise two grating layers 104A, 104B. In someembodiments, the waveguide is formed by sandwiched the grating layersbetween glass or plastic substrates to form a stack within which totalinternal reflection occurs at the outer substrate and air interfaces.The stack may further comprise additional layers such as beam splittingcoatings and environmental protection layers. Each grating layer maycontain an input grating 105A, 105B, a fold grating exit pupil expander106A, 106B and an output grating 107A, 107B where characters A and Brefer to waveguide layers 104A, 104B respectively. The input grating,fold grating and the output grating are holographic gratings, such as aswitchable or non-switchable SBG. As used herein, the term grating mayencompass a grating comprised of a set of gratings in some embodiments.In general, the IIN 103 integrates a microdisplay panel 102, lightsource 101 and optical components needed to illuminate the displaypanel, separate the reflected light and collimate it into the requiredFOV. The IIN 103 projects the image displayed on the microdisplay panelsuch that each display pixel is converted into a unique angulardirection within the substrate waveguide according to some embodiments.In the embodiment of FIG. 1 and in the embodiments to be described belowat least one of the input fold and output gratings may be electricallyswitchable. In many embodiments, all three grating types are passive,that is, non-switching. The collimation optics contained in the IIN 103may comprise lens and mirrors which is some embodiments may bediffractive lenses and mirrors.

In some embodiments, the IIN may be based on the embodiments andteachings disclosed in U.S. Pat. Application No.: 13/869,866 entitledHOLOGRAPHIC WIDE ANGLE DISPLAY, and U.S. Pat. Application No.:13/844,456 entitled TRANSPARENT WAVEGUIDE DISPLAY, the disclosures ofwhich are incorporated herein by reference. In some embodiments, the IINcontains beamsplitter for directing light onto the microdisplay andtransmitting the reflected light towards the waveguide. In oneembodiment, the beamsplitter is a grating recorded in HPDLC and uses theintrinsic polarization selectivity of such gratings to separate thelight illuminating the display and the image modulated light reflectedoff the display. In some embodiments, the beam splitter is a polarizingbeam splitter cube. In some embodiment, the IIN incorporates adespeckler. Advantageously, the despeckler may be a holographicwaveguide device based on the embodiments and teachings of U.S. Pat. No.US8, 565,560 entitled LASER ILLUMINATION DEVICE, the disclosure of whichis incorporated herein.

The light source can be a laser or LED and can include one or morelenses for modifying the illumination beam angular characteristics. Theimage source can be a micro-display or laser based display. LED willprovide better uniformity than laser. If laser illumination is usedthere is a risk of illumination banding occurring at the waveguideoutput. In some embodiments laser illumination banding in waveguides canbe overcome using the techniques and teachings disclosed in U.S.Provisional Pat. Application No.: 62/071,277 entitled METHOD AND OPTICALDISPLAY FOR GENERATING INPUT IMAGES FOR HOLOGRAPHIC WAVEGFUIDE DISPLAYS,the disclosure of which is incorporated herein. In some embodiments, thelight from the light source 101 is polarized. In one or moreembodiments, the image source is a liquid crystal display (LCD) microdisplay or liquid crystal on silicon (LCoS) micro display.

The light path from the source to the waveguide via the IIN is indicatedby rays1000-1003. The input grating of each grating layer couples aportion of the light into a TIR path in the waveguide once such pathbeing represented by the rays 1004-1005. The output waveguides 107A,107C diffract light out of the waveguide into angular ranges ofcollimated light 1006, 1007 respectively for viewing by the eye 108. Theangular ranges, which correspond to the field of view of the display,are defined solely by the IIN optics. In some embodiments, the waveguidegratings may encoded optical power for adjusting the collimation of theoutput. In some embodiments, the output image is at infinity. In someembodiments, the output image may be formed at distances of severalmeters from the eye box. Typically, the eye is positioned within theexit pupil or eye box of the display.

In some embodiments, similar to the one shown in FIG. 1 each gratinglayer addresses half the total field of view. Typically, the foldgratings are clocked (that is, tilted in the waveguide plane) at 45° toensure adequate angular bandwidth for the folded light. However, someembodiments of the invention may use other clock angles to satisfyspatial constraints on the positioning of the gratings that may arise inthe ergonomic design of the display. In some embodiments, at least oneof the input and output gratings have rolled k-vectors. The K-vector isa vector aligned normal to the grating planes (or fringes) whichdetermines the optical efficiency for a given range of input anddiffracted angles. Rolling the K-vectors allows the angular bandwidth ofthe grating to be expanded without the need to increase the waveguidethickness.

In some embodiments, the fold grating angular bandwidth can be enhancedby designing the grating prescription provides dual interaction of theguided light with the grating. Exemplary embodiments of dual interactionfold gratings are disclosed in U.S. Pat. Application No.:14/620,969entitled WAVEGUIDE GRATING DEVICE, the disclosure of which isincorporated herein.

In some embodiments, at least one of the input, fold or output gratingsmay combine two or more angular diffraction prescriptions to expand theangular bandwidth. Similarly, in some embodiments at least one of theinput, fold or output gratings may combine two or more spectraldiffraction prescriptions to expand the spectral bandwidth. For example,a color multiplexed grating may be used to diffract two or more of theprimary colors.

FIG. 2 is a plan view of a single grating layer similar to the ones usedin FIG. 1 . The grating layer 111, which is optically coupled to the IIN103, comprises input grating 105, a first beamsplitter 114, a foldgrating 115, a second beamsplitter 116 and an output grating 107. Thebeamsplitter are partially transmitting coatings which homogenize thewave guided light by providing multiple reflection paths within thewaveguide. Each beamsplitter may comprise more than one coating layerwith each coating layer being applied to a transparent substrate.Typical beam paths from the IIN up to the eye 118 are indicated by therays 1010-1014.

By using the fold grating, the waveguide display may use fewer layersthan previous systems and methods of displaying information according tosome embodiments. In addition, by using fold grating, light can travelby total internal refection within the waveguide in a single rectangularprism defined by the waveguide outer surfaces while achieving dual pupilexpansion. In another embodiment, the input grating, the fold gratingand the output grating can be created by interfering two waves of lightat an angle within the substrate to create a holographic wave front,thereby creating light and dark fringes that are set in the waveguidesubstrate at a desired angle

FIG. 3 illustrates a plan view of a two grating layer configurationsimilar to the ones used in FIG. 1 . The grating layers 121A, 121B whichare optically coupled to the IIN 103 comprise input gratings 105A, 105B,first beamsplitters 114A, 114B, fold gratings 115A, 115B, secondbeamsplitters 116A, 116B and output gratings 107A, 107B, where thecharacters A, B refer to the first and second grating layers and thegratings and beams splitters of the two layers substantially overlap.

In many waveguide configurations, the input, fold, and output gratingsare formed in a single layer sandwiched by transparent substrates. FIG.1 illustrates such stacking in reference to items 104A and 104B. In someembodiments, the waveguide may comprise just one grating layer. In someembodiments, the cell substrates may be fabricated from glass. Anexemplary glass substrate is standard Corning Willow glass substrate(index 1.51) which is available in thicknesses down to 50 micron. Inother embodiments the cell substrates may be optical plastics.

In some embodiments, the grating layer may be broken up into separatelayers. For example, in some embodiments, a first layer includes thefold grating while a second layer includes the output grating. In someembodiments, a third layer can include the input grating. The number oflayers may then be laminated together into a single waveguide substrate.In some embodiments, the grating layer is comprised of a number ofpieces including the input coupler, the fold grating and the outputgrating (or portions thereof) that are laminated together to form asingle substrate waveguide. The pieces may be separated by optical glueor other transparent material of refractive index matching that of thepieces.

Some embodiments may comprise a grating layer be formed via a cellmaking process by creating cells of the desired grating thickness andvacuum filling each cell with SBG material for each of the inputcoupler, the fold grating and the output grating. In one embodiment, thecell is formed by positioning multiple plates of glass with gaps betweenthe plates of glass that define the desired grating thickness for theinput coupler, the fold grating and the output grating. In oneembodiment, one cell may be made with multiple apertures such that theseparate apertures are filled with different pockets of SBG material.Any intervening spaces may then be separated by a separating material(e.g., glue, oil, etc.) to define separate areas.

In other embodiments, the SBG material may be spin-coated onto asubstrate and then covered by a second substrate after curing of thematerial. In some embodiments, the grating in a given layer is recordedin stepwise fashion by scanning or stepping the recording laser beamsacross the grating area. In many embodiments the gratings may berecorded using mastering and contact copying process currently used inthe holographic printing industry.

The embodiment illustrated in FIG. 1 represents a monochrome waveguidedisplay. As an improvement one may utilize a stack of monochromewaveguides to derive a color display as illustrated in FIG. 4 . FIG. 4illustrates a dual axis expansion waveguide display 130 comprising alight source 101 a microdisplay panel 102 and an input image node (IIN)103 optically coupled to red, green and blue waveguides 104R, 104G,104B, which each comprise two grating layers. In order that wave guidingcan take place in each waveguide the three waveguides are separated byair gaps. In some embodiments, the waveguides are separated by a lowindex material such as a nanoporous film. The red grating layer labelledby R contains an input grating 135R, 136R, a fold grating exit pupilexpander 137R, 138R and an output grating 139R, 140R. The gratingelements of the blue and green waveguides are labeled using the samenumerals with B and G designating blue and green. Since the light pathsthrough the IIN and waveguides in each of the red green and bluewaveguides are similar to those illustrated in FIG. 1 they are notsshown in FIG. 4 . In some embodiments, the input, fold and outputgratings are all passive, that is non-switching. In some embodiments, atleast one of the gratings is switching. In some embodiments, the inputgratings in each layer are switchable to avoid color crosstalk betweenthe waveguide layers. In some embodiments color crosstalk is avoided bydisposing dichroic filters 141,142 between the input grating regions ofthe red and blue and the blue and green waveguides.

In some embodiments, a color waveguide may use just one grating layer ineach monochromatic waveguide, as illustrated in FIG. 5 . The embodimentillustrated in FIG. 5 represents a similar configuration as that shownin FIG. 4 with each of the red, green, and blue waveguides (104R, 104G,and 104B) comprising only a single grating layer. Each grating layerhaving an input grating (152R, 152G, and 152B), a fold grating (153R,153G, 153B), and an output grating (154R, 154G, 154B) for each of therespective red, green, and blue layers.

Some embodiments of the waveguide may include an eye tracker. One suchembodiment is illustrated in FIGS. 6, 7, and 8 . The teachings of thevarious embodiments of the eye tracker configuration may be furtherillustrated in PCT/GB2014/000197 entitled HOLOGRAPHIC WAVEGUIDE EYETRACKER, PCT/GB2015/000274 entitled HOLOGRAPHIC WAVEGUIDEOPTICALTRACKER, PCT Application No.: GB2013/000210 entitled OPTICALDISPLAY FOR EYE TRACKING, U.S. Provisional Pat. Application No.:62/176,572 entitled ELECTRICALLY FOCUS TUNABLE LENS, and U.S.Provisional Pat. Application No.: 62/125,089 entitled HOLOGRAPHICWAVEGUIDE LIGHT FIELD DISPLAYS, the disclosures of each of which areincorporated herein by reference. Some embodiments may additionallycomprise a dynamic focus lens as illustrated in FIG. 7 the effect ofwhich is to provide a multiplicity of image surfaces.

In various embodiments of the invention the IIN is optically matched tothe waveguide. Waveguides raise optical interfacing issues that are notencountered in conventional optical systems in particular matching theinput image angular content to the angular capacity of the waveguide andinput grating. The optical design challenge is to match the IIN aperturevariation as a function of field angle to the rolled K-vector inputgrating diffraction direction. In various embodiments the waveguide isdesigned to make the waveguide thickness as small as possible whilemaximizing the spread of field angles at any given point on the inputgrating, subject to the limits imposed by the angular bandwidth of theinput grating, and the angular carrying capacity of the waveguide.

It should be appreciated that coupling collimated angular image contentover the full field of view and without significant non-uniformity ofthe illumination distribution across the pupil requires a NumericalAperture (NA) variation ranging from high NA on one side of themicrodisplay falling smoothly to a low NA at the other side. NA isdefined as being proportional to the sine of the maximum angle of theimage ray cone from a point on the microdisplay surface with respect toan axis normal to the microdisplay. Other equivalent measures may beused for the purposes of determining the most optimal IIN to waveguidecoupling. Controlling the NA in this way will ensure high opticalefficiency and reduced banding and other illumination non-homogeneitiesin the case of LED-illuminated displays. Laser-illuminated displays willalso benefit from the control of NA variation across the microdisplayparticular with regard to homogeneity.

In many embodiments, as illustrated, in FIG. 9 the IIN 103 comprises amicrodisplay panel 251 a spatially-varying NA component 252 andmicrodisplay optics 253. The microdisplay optics accepts light 1060 froman illumination source which is not illustrated and deflects the lighton to the microdisplay in the direction indicated by the ray 1061. Thelight reflected from the microdisplay is indicated by the divergent raypairs 1062-1064 with NA angles varying along the X axis.

Although a particular configuration of the IIN 103 is illustrated inFIG. 9 , it should be understood that a variety of configurations may beused to ensure the most efficient image quality is produced. By way ofexample the spatially-varying NA component may be located adjacent tothe output surface. Additionally, the microdisplay may function as areflective device, as illustrated in FIG. 9 , or may function as atransmission or emissive device.

Furthermore, the spatially-varying NA component may take on a variety ofconfigurations having a uniformly varying NA characteristic. Variousexemplary embodiments are illustrated in FIGS. 10-13 . Some embodimentsmay include a wedge as illustrated in FIG. 10 while others may bevariations of such. FIG. 11 illustrates a spatially-varying NA componentin a curved wedge format. FIG. 12 illustrates an exemplary embodimentwherein the NA component comprises an array of a plurality of prismaticelements having differing prism angles. Additionally, some NA componentsmay comprise an array of lenses with various apertures and opticalpowers, as illustrated in FIG. 13 .

In addition to the various profile characteristics illustrated in FIGS.10-13 , spatially-varying NA components may comprise a variety ofsurface features or internal substrate configurations designed with avariety of scatter elements. FIG. 14A illustrates a spatially-varying NAcomponent having a scatter element integrated with the surface texture.FIG. 14B illustrates a substrate of the spatially-varying NA componenthaving scattering properties as part of the base substrate. Suchproperties may come from a variety of configurations that may includeindividual scatter components suspended within the body of thesubstrate.

In some embodiments, such as the one illustrated in FIG. 14C aspatially-varying NA component 286 comprises a birefringent substrate287 having a spatially varying birefringence as represented by theuniaxial crystal index functions 288A, 288B. In some embodiments, thesubstrate provides a continuous variation of birefringence. In someembodiments, the substrates comprise discrete elements each have aunique birefringence. In some embodiments, a spatially-varying NAcomponent is a scattering substrate with birefringent properties. Insome embodiments, a spatially-varying NA component is based on any ofthe embodiments of FIGS. 10-13 implements using a birefringentsubstrate. In some embodiments, the NA variation across the field isperformed using a birefringent layer having comprising a thin substratecoated with a Reactive Mesogen material. Reactive Mesogens arepolymerizable liquid crystals comprising liquid crystalline monomerscontaining, for example, reactive acrylate end groups, which polymerizewith one another in the presence of photo-initiators and directional UVlight to form a rigid network. The mutual polymerization of the ends ofthe liquid crystal molecules freezes their orientation into athree-dimensional pattern. Exemplary Reactive Mesogen materials aremanufactured by Merck KgaA (Germany).

In some embodiments, such as the one illustrated in FIG. 14D aspatially-varying NA component 286 comprises an array of diffractiveelements each characterized by a unique K-vector and diffractionefficiency angular bandwidth. For example element 289A at one end of thecomponent has k-vector K₁ and bandwidth ΔΘ₁ configured to provide a highNA while element 289B at the other end has k-vector K₂ and bandwidth ΔΘ₂configured to provide a low NA. In some embodiments, the gratingcharacteristics vary continuously across the substrate. In someembodiments, the gratings are Bragg holograms recorded in HPDLCmaterials. In some embodiments, the gratings are surface reliefgratings. In some embodiments, the gratings are computer generateddiffractive structures such as computer generated holograms (CGHs).

In some embodiments, the IIN design addresses the NA variation problem,at least in part, by tilting the stop plane such that its normal vectoris aligned parallel to the highest horizontal field angle, (rather thanparallel to the optical axis). As illustrated in FIG. 15 the IIN 287 isconfigured to provide an output field of view of half angle Θ defined bythe limiting rays 1086A, 1086B disposed symmetrical about the opticalaxis 1087. The stop plane 1088 is normal to the limiting ray 1086B. Itis assumed that the waveguide input grating, which is not illustrated,couples the horizontal field of view into the waveguide (not shown).

Although the present application does not assume any particularconfiguration of the microdisplay optics 253, further embodiments may befurther represented in U.S. Pat. Application No.: 13/869,866 entitledHOLOGRAPHIC WIDE ANGLE DISPLAY, and U.S. Pat. Application No.:13/844,456 entitled TRANSPARENT WAVEGUIDE DISPLAY, the disclosures ofwhich are incorporated herein. In some embodiments, the microdisplayoptics contains at least one of a refractive component and curvedreflecting surfaces or a diffractive optical element for controlling thenumerical aperture of the illumination light. In some embodiments, themicrodisplay optics contains spectral filters for controlling thewavelength characteristics of the illumination light. In someembodiments, the microdisplay optics contains apertures, masks, filter,and coatings for controlling stray light. In some embodiments, themicrodisplay optics incorporate birdbath optics.

FIG. 16 shows schematic front views of two waveguide grating layoutsthat may be provided by the invention. In the embodiment of FIG. 16A thewaveguide 300 comprises a shaped waveguide comprising in a single layerindicted by 1086 an input grating 302, a fold grating 303 and an outputgrating 304. The K-vectors of the three gratings (that is the normalvector to the fringes shown inside each grating) are indicated by1083-1084. Note that in each case the K-vector is projected in the planeof the drawings. In the embodiment of FIG. 16B the waveguide 310comprises a shaped waveguide comprising in a single layer indicted by1090 an input grating 313, a fold grating 314 and an output grating 315.The K-vectors of the three gratings (that is the normal vector to thefringes shown inside each grating) are indicated by 1087-1089. In eachcase the K-vector is projected in the plane of the drawings.

FIG. 17 shows a further general waveguide grating layout that may beprovided by the invention. The waveguide 320 comprises a rectangularwaveguide comprising in a single layer an input grating 322, a foldgrating 323 and an output grating 324. The K-vectors of the threegratings (that is the normal vector to the fringes shown inside eachgrating) are indicated by 1091-1093. In each case the K-vector isprojected in the plane of the drawings. The fold grating in this casehas Bragg fringes aligned at 45 degrees in the plane of the grating

Embodiments of Wearable HUDs

Turning now to FIGS. 18A and 18B. In many embodiments, the waveguidedisplay is coupled to the IIN 103 by an opto-mechanical interfacethereby allowing the waveguide to be easily retracted from the IINassembly. The basic principle is illustrated in FIG. 18A which shows adual axis expansion waveguide display 200 comprising the waveguide 201containing the input grating 105, fold grating 106 and output grating107 and the IIN 103. The optical display further comprises an opticallink 206 connected to the waveguide, a first optical interface 207terminating the optical link and a second optical interface 208 formingthe exit optical port of the IIN. The first and second opticalinterfaces can be decoupled as indicated by the gap 209 illustrated inFIG. 18B. In some embodiments the optical link may be a waveguide itselfoptically designed to work with the main waveguide display 104. In someembodiments, the optical link is curved. In some embodiments, theoptical link is a GRIN image relay device. In many embodiments, theoptical connection is established using a mechanical mechanism. In someembodiments, the optical connection is established using a magneticmechanism. The advantage of decoupling the waveguide from the IIN inhelmet mounted display applications is that the near eye portion of thedisplay be removed when not in used. In some embodiments where thewaveguide comprises passive gratings the near eye optics can bedisposable

As discussed above, in some embodiments such as the one illustrated inFIGS. 18A - 19C the waveguide display is coupled to the IIN by anopto-mechanical interface that allows the waveguide to be easilyretracted from the IIN assembly. FIG. 19A shows a removable near eyedisplay 290 comprising a near eye waveguide component 291 and an IIN103. The waveguide component includes an opto-mechanical interface 292configured to optically match the IIN and removably connect to theopto-mechanical interface of the IIN 294. The waveguide component 291can have at least two configurations with respect to the IIN. Asillustrated by FIG. 19A the waveguide component 291 is in a removed orretracted configuration. The waveguide is shown retracted from the IINassembly. FIG. 19B shows a second 3D view of the HMD 296 with thewaveguide component retracted. FIG. 19C illustrates a connected positionof the waveguide component 291 wherein the component isopto-mechanically connected to the IIN 103.

FIGS. 20A-21B illustrate an exemplary embodiment of a waveguide displaythat may be integrated into a helmet. FIGS. 20A-20D illustrate front,plan, side, and three-dimensional views of one eyepiece of a dual axisexpansion display that may be used in a helmet mount display. One suchembodiment may be in a motorcycle helmet. The display comprises thewaveguide 104, input grating 105, fold grating 106, output grating 107;which were previously described in more detail. Additionally, thewaveguide display of FIGS. 20A-20D may include a hinge mechanism 235 forattaching the display to the helmet and the waveguide coupling mechanism236 configured to opto-mechanically couple to the IIN assembly.

FIG. 21A and FIG. 21B show a frontal view and a side view of a HUDeyepiece integrated in a helmet. Although a particular helmetconfiguration is shown it should be understood that any acceptableconfiguration may be implemented.

Turning now to FIG. 22 , an exemplary embodiment of a HUD 330 waveguidedisplay is thus illustrated. FIG. 22 illustrates a waveguide display inthe form of a near eye display. The near eye display comprises an IINassembly 331 and a waveguide component 291 opto-mechanically coupled tothe IIN assembly 331. The waveguide component further comprises an inputgrating 105 a fold grating 106 and an output grating 107. Although notshown here the waveguide component is further configured with anopto-mechanical interface 353 for coupling the waveguide to the INNassembly 331. The waveguide path from entrance pupil 2000 through theinput grating, fold grating and output grating and up to the eye box2005 is represented by the rays 2001-2004.

FIGS. 23A and 23B provide illustrations of various operational positionsaccording to the invention whereby the HUD 330, as illustrated in FIGS.22 and 19A-19C, is provided as a HMD integrated in a helmet. In such anembodiment the IIN assembly 331 may form part of the helmet or may beadded aftermarket. Similar to FIGS. 19A and 19B, FIG. 23A illustrates aHUD display 330 in a first operational state 341 in which the waveguidecomponent 291 is fully retracted from the IIN assembly 331. Similarly,FIG. 23B illustrates the display in a second operational state 342 withthe waveguide component 291 coupled to the IIN assembly.

In many embodiments, such as the one illustrated in FIG. 24 , a displayaccording to the principles of the invention comprises an IIN assembly331 a waveguide eyepiece 352 (which is part of the overall waveguidecomponent previously described) and prismatic relay optics 353. The IINcontains at least the microdisplay panel 351A illuminated by a lightsource which is not shown and projection optics 2010 which typicallycomprises refractive optics. The IIN assembly 331 is coupled to theprismatic relay optics by a coupler assembly 354 which providesmechanical support and an optical connection to admit light from the IINassembly 331 into the prismatic relay optics 353. The prismatic relayoptics comprises a reflective surface 353A which may be a TIR surface ormay alternatively support a reflective coating. Light from the prismaticrelay optics 353 is coupled into the waveguide eyepiece 352 via theoptical interface layer 355 which in some embodiments providespolarization selectivity. In some embodiments, the optical interfacelayer 355 provides one of spectral or angular selectivity. In someembodiments, the optical interface layer 355 is a diffractive opticalelement. In some embodiments, at least one of the transmitting orreflecting surfaces of the prismatic relay optics has optical power. Insome embodiments, at least one of the transmitting or reflectingsurfaces of the prismatic relay optics supports at least one coating forcontrolling at least one of polarization, reflection or transmission asa function of wavelength or angle. The image light from the IIN isexpanded in the prism to produce sufficient beam width aperture toenable a high efficiency “Roll-K Vector” input aperture - thuspreserving efficiency and brightness.

In some embodiments, the waveguide eyepiece 352 comprises input, foldand output gratings disposed in separate red, green and blue diffractinglayers or multiplexed into fewer layers as discussed above. Forsimplicity, the gratings in FIG. 24 are represented by the input grating352A, fold grating 352B and output grating 352C. The light path from theprojector through the prismatic relay optics and the waveguide isrepresented by the rays 2010-2013. The output image light viewed by theeye 356 is represented by the rays 2014 and 2015. The rays 2016 and 2017illustrate the transparent of the waveguide to external light forward ofthe eyepiece and the transparency of the prismatic relay optics toexternal light in the periphery of the display wearer’s field of view.

In some embodiments, based on the above described display architectures,may also implement a photodetector for detection of ambient light levelsfor the purpose of matching the display image luminance to the externalscene luminance. Although, not shown in in the figures, suchphotodetectors may be integrated into the helmet structure orelectromechanically connected to the HUD display.

Additionally, although it is largely represented in the figures in oneconfiguration it should be noted that the prismatic relay optics maytake on any suitable configuration. As illustrated in FIGS. 24 and 27 ,the prismatic relay optics comprise an elongated prism form whereas forexample FIGS. 40A-40F illustrate a prismatic relay optics as beinglargely flat. In some embodiments the prismatic relay optics may beintegrated within or right next to the IIN assembly.

One exemplary embodiment of the invention for use in a helmet HUD isillustrated FIGS. 27-39 which illustrate details of the waveguideeyepiece, IIN, and associated prismatic relay optics linking the IIN andwaveguide eyepiece. Design specifications in accordance with manyembodiments of the invention are illustrated by the table in FIG. 25 .Such specifications include the Eye box size, focal distance and imageresolution, and are presented for exemplary purposes only.

FIG. 26A and FIG. 26B provide a schematic front and side elevation viewsa helmet HUD. As described in other figures, the display comprises awaveguide eye piece 352, prismatic relay couple 353 and the IIN assembly331. Additionally, FIGS. 26A and 26B illustrate one embodiment of theHUD integrated with a helmet where the HUD’s spatial relation withrespect to the Helmet visor 373 is shown. In accordance with manyembodiments of the invention, where the HUD is integrated with a helmetas illustrated in FIGS. 26A and 26B, the waveguide eyepiece 352 may betilted (rake angle) to the horizontal plane to avoid the visor. Invarious embodiments the rake angle may be at least 20 degrees, inaccordance with many embodiments, the rake angle is at least 25 degrees,which enables eye-relief at least 25 mm while providing generous visorclearance. In many embodiments the design allows the eyepieces totranslate between the left and right sides of helmet.

In accordance with other embodiments FIG. 27 illustrates a detail of theheadpiece HUD comprising the waveguide eyepiece 352, the prismatic relayoptics 353, and a frame or coupler 354, which may serve as theopto-mechanical coupling between the waveguide component and the IIN. Inaccordance with some embodiments the frame or coupler 354 may comprise amechanical attachment point that may be selected from a group consistingof a magnet, hinge, or USB connection. In many embodiments the prismaticrelay optics are visually transparent to allow ambient light and ensureincreased field of vision of the user. In accordance with manyembodiments the prism assembly also comprises a corner coupler moldingand beam splitter window 355 and a prism window 353B.

In accordance with many embodiments of the invention the opto-mechanicalcoupler 354 that couples the prismatic relay optics 353 to the IIN 331as illustrated in FIGS. 26-30 represents a component of the HUD display.The coupler 354 may comprise a plurality of alignment characteristicssuch as magnets, pins, or other physical characteristics to ensure theproper optical alignment of the IIN, the prismatic relay optics, and thewaveguide. Under the principles previously discussed the alignment ofthe image produces by the IIN with the waveguide may be used to ensure aquality image via the output grating. In many embodiments, the angle atwhich the image is projected from the IIN through the prismatic relayoptics and subsequently to the waveguide display is maintained at aninput angle configured for the particular optical characteristicsdesired such that total internal reflection is thus maintained.Therefore, the opto-mechanical coupler 354, in accordance with manyembodiments, may be fabricated to accurately align the optical output ofthe IIN with the input grating of the waveguide at an input angle thusensuring total internal reflection is maintained. Such alignment inaccordance with some embodiments is thus illustrated in FIG. 27 by wayof the mechanical design of the coupler with an optical window 376B andmechanical magnetic connection points 376A. Additional alignment methodsare thus illustrated for example in FIGS. 40A-40F where the prismaticrelay optics comprises a relatively flat component.

FIG. 28 illustrates an opto-mechanical coupling between the IIN and thewaveguide component. In accordance with many embodiments, the IINassembly 331 may also comprise a HDMI, DigiLens switch, power on/offswitch and a photodiode PCB as generally indicated by 331B through 331E.As shown in FIG. 28 the IIN also comprises a microdisplay connector 377.

In accordance with many embodiments of the invention, FIG. 29 shows anexploded view detail of the HUD display without the IIN. The figureshows the waveguide eye piece 352, prismatic relay optics and coupler353 and 354 respectively. The prism relay optics 353 provides a pathlinking the IIN to the waveguide eyepiece and due to its transparencyalso provides an enhanced peripheral field of view. The waveguideeyepiece, shown in exploded view, further comprises red, green and bluelayers 352R, 352G, 352B encased between two layers of optical film 352A,352B. Such film may consist of a polymer type material such that itprovides wipe-clean, ballistic anti-shatter protection. Additionally,the optically sound waveguide eyepiece 352 may be encased by a clearsurround molding 3352D. In accordance with many embodiments and toconnect the power inputs of the IIN with that of the waveguide eyepiececomponents, a flex cable 374E may be used.

Turning now to FIG. 30 and in accordance with many embodiments anillustrative view of the HUD in a helmet is represented. FIG. 30illustrates the HUD with the waveguide eyepiece 352 opto-mechanicallyconnected to the prismatic relay optics 353 which opto-mechanicallyconnect to the IIN 331 via an opto-mechanical coupling. Additionally,FIG. 30 illustrates the optimal field of view both horizontally andvertically with respect to the HUD when attached to a helmet, asillustrated via the blue and red degree lines. Maintaining adequateField of View (FOV) angles is another element in the design of theprismatic relay optics. FIG. 31 further illustrates a preferredembodiment of the prismatic relay optics wherein the peripheral FOV isat least 25 degrees.

In accordance with many embodiments of the invention the IIN maycomprise various optics and communications components. As illustrated inFIG. 33 , many embodiments of the IIN may include a power switch 331L,various communication cables 331J, a cooling fan 331E, and other PCBcomponents 331K that are electrically connected to the picoprojector andother optical components of the IIN. As described previously the IINoperates to generate an image and project the image through theprismatic relay optics at the preferred angle such that the image isultimately displayed via the output gratings of the waveguide eyepiece.

Maintaining ideal temperatures of the electrical optical components maybe implemented to ensure the waveguide eyepiece function. Therefore, inaccordance with many embodiments a cooling fan 331E is illustrated inFIGS. 33-35 . An exemplary fan for use with the invention is the modelUF3A3-700manufactured by Sunonwealth Electric Machine Industry (China).The fan which has a volume of 10x10x3 mm provides an air flow of 3.43liter/minute. The noise level is 21.0 dB(A) / 30 cm. Using a cooling fanof this specification it is possible to meet current 40-degree thermalrequirement specifications for motorcycle helmets.

Additionally, as illustrated in FIGS. 31-35 and 38-39 , in manyembodiments the components of the IIN assembly are collocated within ahousing that facilitates the opto-mechanical coupling between thewaveguide component and the IIN. In accordance with many embodiments thehousing has a minimum wall thickness (e.g., less than 2 mm) to enhancethe conduction heat away from the internal components. In manyembodiments the IIN assembly may be integrated with the helmet itself ormay be subsequently attached thereto.

In accordance with many embodiments, a method of attaching the HUD unitto a helmet is presented. Turning to FIGS. 36 and 37 a method ofattaching the HUD is illustrated. FIG. 36 illustrates the use of asupporting headband 473 that surrounds the users head and has aplurality of securing fixtures 471 attached thereto. The securingfixtures are configured to interconnect the supporting headband to theinside of a helmet. The securing fixtures may consist of a variety ofdevices including temporary hook and loop fasteners or more permanenttype fasteners. The supporting headband is additionally configured toreceive the HUD by way of an interconnection bracket. Theinterconnection bracket 474 may be configured to be adjustable along thelength of the supporting headband 473 such that the position of the HUDcan be adjusted to the most comfortable position of the user.Additionally, in accordance with many embodiments the interconnectionbracket may be configured to allow multiple axis of adjustment 2040 ofthe HUD such that when the IIN connects thereto it would thereby allowthe user to adjust the position of the HUD to maintain the greatest FOV.FIGS. 36 and 37 illustrate the desired FOV through the variousadjustments positions of the HUD. Although a particular configuration isillustrated in FIGS. 36 and 37 it should be understood that any suitableconfiguration may be adopted. In accordance with many embodiments FIG.38 illustrates a manner of configuration of the HUD integrated with ahelmet such that the desired user FOV is maintained.

In accordance with many embodiments the IIN comprises a picoprojectorgroup 378 as illustrated in FIG. 39 (other views are also illustrated inFIGS. 31-35 ). The picoprojector group may further comprise a firstprojection lens group 378A, a second lens group 378B for collimating thelight reflected from the microdisplay 378C. Although not shown in thefigures the picoprojector may further comprise an LED illuminator andLED illumination optics. In addition to the optical components, the IINmay further comprise an LED Heatsink 379 that may coordinate with theaforementioned fan to maintain the optimal thermal specifications. TheIIN also comprises a microdisplay video controller PCB 377E. In someembodiments the IIN may contain separate rechargeable power cells forpowering the various internal components. Ray paths through theprojector are indicated by 2030 and in the prismatic relay element by2031, thereby illustrating the projected optimal path of the image.

In accordance with many embodiments of the invention the HUD may beconfigured to be removable from a helmet configuration such that whennot in use it may be properly stored and if applicable charged forfuture use. FIGS. 40A-40F illustrate an exemplary embodiment of theinvention in which the IIN is configured to be removable from anelectromechanical attachment point collocated in/on the helmet. In someembodiments the IIN may attach to the helmet via a magnetic connection.In other embodiments the connection may involve a variety of attachmentconfigurations including a hinge or a USB type connection. Additionally,the IIN assembly may be configured with a communication port such thatit may be in communication with other components of a helmet includingBluetooth connectivity and/or GPS. In other embodiments, although notillustrated in FIGS. 40A-40F, the attachment/detachment point may bebetween the waveguide component and the IIN. In such embodiments thewaveguide component may be fully removed and properly stored when not inuse.

In accordance with many embodiments the prismatic relay optics 353 asillustrated in FIGS. 41A-41B, projects the beam from the pico projectorlocated within the IIN 331. The beam will expand in the prism to allowfor sufficient aperture to enable a high efficiency “Roll-K Vector”input aperture, thus preserving the efficiency and brightness of theprojected image. The brightness of the image is also maintained throughthe various controllers in the IIN. For example, as illustrated in FIG.50B, light and temperature sensors, 640 and 650 respectively, may belocated within the IIN to accommodate for changes in ambient temperatureand light.

According to many embodiments the IIN 331, as mentioned previously alsoincludes mechanisms such as fans and LED heatsinks that help to regulatethe temperature to ensure the most efficient image production. FIG. 42Aillustrates an ambient air intake 410 situated within the housing of theIIN. Additionally, FIG. 42B illustrates a conditioned air outtake 420situated within the IIN housing. Furthermore, the IIN may includeinternal passive heat dissipation components 480 as illustrated in FIG.49B. Such passive components may include fins or LED heatsinks asmentioned previously. Additionally, to ensure the most efficient imageproduction the IIN and the opto-mechanical connection may includealignment magnets 440 and precision electrical connections 430. Theelectrical connections may, according to some embodiments, create thepower connections between the various red, green, blue, or mono-colorgrating layers within the waveguide. Such connection may be configuredto maintain an image quality from the IIN to the output grating. Inaccordance with many embodiments FIG. 43A illustrates the magnetic andelectrical connections between the IIN and the prismatic relay.

FIG. 43B further illustrates the magnetic and electrical connectionslocated within the IIN in accordance with some embodiments of theinvention. Such connection may be one of several that exist on the IIN.The connection, in accordance with many embodiments of the invention maybe configured to avoid a ghosting effect on the final image. Ghosting isspurious colors in the image due to inaccuracies in the individualwaveguide light path (as created via the opto-mechanical connections)including glass flatness and can be affected by poor connections.Although specific embodiments of interconnection are shown, it will beunderstood that the electrical and alignment connections may take on anysuitable form that produces a precise alignment.

In accordance with many embodiments the HUD may be configured to mounton a helmet or other headpiece. As illustrated in FIGS. 44A-44B, oneembodiment is shown where the power and other communication connections480 are housed within a bracket 470. The bracket may have an alignmentfeature that correlates to a feature on the IIN such that the IINsecurely aligns and connects to the helmet. Such connection may take onany number of forms and may include a magnetic connection 445/446 oneither side of the connection. As further illustrated in FIG. 45 thealignment bracket 470 may be adjustable such that it can be configuredto attach to any number of suitable head pieces or helmets.

In accordance with many embodiments, as previously discussed, the HUDmay be configured to be adjustable within the helmet or head piece. FIG.46-47B as well as FIGS. 36-38 illustrate embodiments of adjustable HUDs.In many embodiments the wearer may be wearing corrective lenses and thuswould need to adjust the HUD accordingly so as not to interfere with thelenses and further provide the highest quality of image. As illustratedin FIG. 36 the attachment points may be fully adjustable. As illustratedin FIG. 46-47B, the rake angle may be adjusted such that the HUD doesnot interfere with the corrective lenses as applicable. Additionally, ascan be seen in FIGS. 47A-47B the waveguide 352 and the IIN 331 can beadjusted to not interfere with corrective lenses 500 or the internalface shield 372 of the helmet. In some embodiments the IIN can beadjusted horizontally (e.g., up to 10 mm) as needed. Additionally, insome embodiments the rake angle can be adjusted (e.g., to be within25-28 degrees).

FIG. 48 in accordance with some embodiments of the invention illustratesthe movement of the HUD with respect to the installation bracket of thedesired headpiece. It should be understood that the bracket may take onany suitable form depending on the headpiece. According to manyembodiments the bracket 470 and the IIN 331 may contain power cables andother communication connections such as HDMI or USB. For example, insome embodiments the IIN may contain a USB-C or other connection builtwithin the PCB and other controllers, as shown in FIGS. 49A and 49B.

In accordance with some embodiments the HUD may be configured to attachto a head piece that may be retrofitted to a helmet or other device. Asillustrated in FIGS. 50A and 50B, the HUD may connect to a headband thatcould be used while running or may be used as a retrofit to any helmet.

Because the IIN requires power to control the projectors and produce theimage on the waveguide, many embodiments may include a separate powersupply. As illustrated in FIG. 51 , a separate power supply 600 unit maybe located at the rear of the helmet or head piece. The power supply maycontain electrical connections between the IIN and the power supply.Such connections may also be integrated within the headband or may beseparate and routed through the internal portion of a helmet 610.Additionally, the power supply 600, being mobile, may be configured witha charging port such that it may be recharged as needed.

In some embodiments, a waveguide display according to the principles ofthe invention may provide a HUD for use in road vehicles in which imagelight is reflected off the windscreen into the driver’s eye box. FIG. 52is a schematic view of a waveguide display embodiment 540 for car HUDapplication with a correction element for compensating for windscreencurvature distortion in one embodiment. The optical display forconfiguration within a car interior 541 comprises the IIN 542, awaveguide 543 for projecting image light onto a windscreen 544 and acorrection element 545 which has a prescription designed to balance thewavefront distortion of light reflected off the windscreen. In someembodiments, the correction element is a refractive element. In someembodiments, the correction element is a diffractive element. In someembodiments, the correction element is a plastic optical element. Insome embodiments, the waveguide contains at least one birefringencecompensation layers designed to balance the birefringence of a plasticcorrection element place in the path between the waveguide and the eyebox. The light path from the waveguide to the eye via the reflection offthe windscreen is illustrated by the rays 1050, 1052. The intersectionof the image light with the windscreen and the eye box is indicated by1051, 1053. The virtual ray path 1054 up to the virtual image 1055 isalso shown.

In some embodiments, a dual expansion waveguide display according to theprinciples of the invention may be integrated within a window, forexample, a windscreen-integrated HUD for road vehicle applications. Insome embodiments, a window-integrated display may be based on theembodiments and teachings disclosed in U.S. Provisional Pat. ApplicationNo.: 62/125,064 entitled OPTICAL WAVEGUIDE DISPLAYS FOR INTEGRATION INWINDOWS and U.S. Provisional Pat. Application No.: 62/125,066 entitledOPTICAL WAVEGUIDE DISPLAYS FOR INTEGRATION IN WINDOWS, the disclosuresof which are incorporated herein by reference. In some embodiments, adual expansion waveguide display may include gradient index (GRIN)wave-guiding components for relaying image content between the IIN andthe waveguide. Exemplary embodiments are disclosed in U.S. ProvisionalPat. Application No.: 62/123,282 entitled NEAR EYE DISPLAY USINGGRADIENT INDEX OPTICS and U.S. Provisional Pat. Application No.:62/124,550 entitled WAVEGUIDE DISPLAY USING GRADIENT INDEX OPTICS, thedisclosures of which are incorporated herein by reference. In someembodiments, a dual expansion waveguide display may incorporate a lightpipe for providing beam expansion in one direction based on theembodiments disclosed in U.S. Provisional Pat. Application No.:62/177,494 entitled WAVEGUIDE DEVICE INCORPORATING A LIGHT PIPE. In someembodiments, the input image source in the IIN may be a laser scanner asdisclosed in U.S. Pat. No. 9,075,184 entitled COMPACT EDGE ILLUMINATEDDIFFRACTIVE DISPLAY, the disclosures of which are incorporated herein byreference. The embodiments of the invention may be used in wide range ofdisplays including HMDs for AR and VR, helmet mounted displays,projection displays, heads up displays (HUDs), Heads Down Displays,(HDDs), autostereoscopic displays and other 3D displays.

Some of the embodiments and teachings of this disclosure may be appliedin waveguide sensors such as, for example, eye trackers, fingerprintscanners and LIDAR systems.

It should be emphasized that the drawings are exemplary in nature andeven though particular embodiments are illustrated the design may takeon any suitable configuration. Optical devices based on any of theabove-described embodiments may be implemented using plastic substratesusing the materials and processes disclosed in PCT Application No.:PCT/GB2012/000680, entitled IMPROVEMENTS TO HOLOGRAPHIC POLYMERDISPERSED LIQUID CRYSTAL MATERIALS AND DEVICES, the disclosure of whichis incorporated herein by reference. In some embodiments, the dualexpansion waveguide display may be curved.

The construction and arrangement of the systems and methods as shown inthe various exemplary embodiments are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (for example, variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.). For example, the position of elements may bereversed or otherwise varied and the nature or number of discreteelements or positions may be altered or varied. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure. The order or sequence of any process or method stepsmay be varied or re-sequenced according to alternative embodiments.Other substitutions, modifications, changes, and omissions may be madein the design, operating conditions and arrangement of the exemplaryembodiments without departing from the scope of the present disclosure

Although the description above contains many specificities, these shouldnot be construed as limiting the scope of the invention but as merelyproviding illustrations of some of the presently preferred embodimentsof the invention. Various other embodiments are possible within itsscope. Accordingly, the scope of the invention should be determined notby the embodiments illustrated, but by the appended claims and theirequivalents.

What is claimed is:
 1. An optical display, comprising: a first waveguidehaving a first set of surfaces comprising a first open space disposedtherebetween; at least one input grating disposed between the first setof surfaces and configured to receive an image from an Input Image Nodeassembly; at least one fold grating optically connected to the at leastone input grating and disposed between the first set of surfaces; atleast one output grating optically connected to the at least one foldgrating and disposed between the first set of surfaces; a prismaticrelay optics opto-mechanically disposed between the input image nodeassembly and the first waveguide; an opto-mechanical coupler disposedbetween the prismatic relay optics and the input image node assembly,wherein the first opto-mechanical coupler is configured to support theprismatic relay optics and receive a collimated first wavelength imagemodulated light and to cause the light to travel within the prismaticrelay optics via total internal reflections to the first waveguide; andan optical interface coupler disposed between the prismatic relay opticsand the first waveguide wherein the optical interface coupler isconfigured to receive the wavelength image modulated light as reflectedwithin the prismatic relay optics and optically communicate said imageto the first waveguide wherein the image will be reflected within thefirst waveguide via total internal reflection between said first set ofsurfaces from the at least one input grating to the fold grating;wherein said fold grating is configured to provide pupil expansion in afirst direction and to direct said light to the output grating via totalinternal reflection between the first set of surfaces; and wherein saidoutput grating is configured to provide pupil expansion in a seconddirection different than said first direction and to cause said light toexit said first waveguide from said first set of surfaces.
 2. Theoptical display of claim 1, wherein the input image node assemblyfurther comprises an outer body having a thickness and an internalcavity wherein disposed within the cavity is at least one light sourceand at least one microdisplay panel for displaying image pixels andcollimation optics, and wherein the input image node assembly isconfigured to project an image displayed on said microdisplay panelwithin the prismatic relay optics at a critical angle thereby ensuringthe image is transmitted to the waveguide at the critical angle thuspreserving the total internal reflection of the image.
 3. The opticaldisplay of claim 1, wherein at least one of said gratings is switchablebetween a diffracting and non-diffracting state.
 4. The optical displayof claim 1, further comprising a second waveguide comprising a secondset of surfaces having a second open space there between and, an inputgrating, a fold grating, and an output grating, wherein the inputcoupler is configured to receive a second wavelength light from theinput image node assembly.
 5. The optical display of claim 1, wherein atleast one of at least one input grating, the at least one fold grating,and the at least one output grating are comprised of a liquidcrystal-based grating.
 6. The optical display of claim 1, furthercomprising an eye tracker.
 7. The optical display of claim 1, furthercomprising a dynamic focus lens disposed within the Input image nodeassembly.
 8. The optical display of claim 1, further comprising adynamic focus lens disposed in proximity to the first set of surfaces ofthe first waveguide.
 9. The optical display of claim 1, wherein theopto-mechanical coupler and the optical interface coupler are configuredto be coupled or decoupled via at least one mechanical interface whereinthe at least one mechanical interface of the opto-mechanical coupler isdisposed between the opto-mechanical coupler and the input image nodeassembly and the at least one mechanical interface of the opticalinterface coupler is disposed between the optical interface coupler andthe prismatic relay optics.
 10. The optical display of claim 9 whereinthe at least one mechanical interface of each of the opto-mechanicalcoupler and optical interface coupler is selected from a groupconsisting of hinged and magnetic.
 11. The optical display of claim 9,wherein said first waveguide is disposable.
 12. The optical display ofclaim 1, wherein the first set of surfaces are a ballistic shatter proofpolymer.
 13. The optical display of claim 1 wherein the first set ofsurfaces are planar surfaces.
 14. The optical display of claim 1,wherein the first set of surfaces are curved.
 15. The optical display ofclaim 1, wherein the input image node assembly further comprises a laserscanner.
 16. The optical display of claim 1, wherein the display isfurther configured to be removably connected to a headpiece.
 17. Theoptical display of claim 16, wherein the input image node assembly isfurther configured to be adjustably connected to the headpiece such thatthe waveguide may be optimally adjusted and wherein the waveguide may bedecoupled for replacement or storage.
 18. The optical display of claim1, wherein the input image node assembly is configured to be integratedwithin an internal protection material of a helmet.
 19. The opticaldisplay of claim 18 where in the input image node assembly is furtherconfigured to be adjustable such that the waveguide may be optimallyadjusted.
 20. The optical display of claim 16, wherein the waveguide isconfigured to be adjustable such that the rake angle may be optimallyadjusted.